In many situations it is desirable to permanently attach a tube to a plate through an aperture therein and various crimping or swaging procedures have been proposed to complete such a mounting operation. The U.S. Pat. Nos. 3,119,435 and 3,140,540 to Greenman show examples of one known method and apparatus for expanding the ends of tubes to join them permanently to a web or plate means or the like. In Greenman, the end of the tube is first performed in one operation to have a collar near its end and then in a second step the tube and plate means are assembled while the ultimate end of the tube is then deformed to complete the attachment of the tube to the apertured element.
Another U.S. Pat. No. 3,778,090 to Tobin, shows alternate methods using either a two or three step crimping process for connecting a tube with a so-called tube block. As here shown, in one method a cooperative die set is used to form an initial bead in the tube together with additional extruded antirotational splines and thereafter one of the elements of the first die set is removed and a second die means is used to crimp an O ring seal in place between the tube and its tube block. In the alternate method, two additional die means are used to complete the swaging of the end of the Tobin tube.
The U.S. Pat. No. 3,280,454 to Rich et al. shows a machine for attaching rungs in the side channels of a ladder wherein one of the side rails of a ladder is carried on very stiff springs while an outer flange is formed on the extending free end of a tube that serves as a rung of the ladder and then an inner flange is formed on the same rung on the other side of the web side channel after the back pressure of the springs has been overcome. In this procedure, the male die element and the female die coact to produce the flanges while the aperture in the web of the side rail of the ladder serves as a divider to guide the location of wrinkling of the tube whereby to form the flanges.
Other less pertinent prior art disclosures showing more complicated procedures to reach somewhat the same end result are seen in U.S. Pat. Nos. 866,644 to Green, 2,535,403 to Froggatt and 3,766,631 to Scheitlin et al.